The number of ways in which a document, such as a check or another value document, can be attacked (i.e., fraud can be committed) is limited only by the imagination and skills of the attacker. In the case of checks, the spectrum of attacks generally falls onto three main classes: counterfeiting, tampering, and re-origination. Counterfeiting is the creation of a copy of a valid check, such as by digital or optical means. Tampering is the process of altering an authentic check to change the payee and/or the amount of the check. Re-origination is the creation of a new check from the scanned background of a valid check or from stolen authentic check stock.
A number of different check security features, such as safety paper and background printing, have been developed to combat and prevent these fraudulent activities. These features have been effective due largely to the fact that traditionally, the actual physical presentation of checks to be deposited was necessary because, under prior banking laws, the depository bank had to present the original of each check to the corresponding paying bank in order to clear the check. This changed in October of 2004 with the enactment of The Check Clearing for the 21st Century Act, commonly referred to as Check 21. Check 21 removed the legal requirement that an original paper check had to be presented to obtain payment. Instead, banks can now use digital images to transport check data from the bank of first deposit to the paying bank. If the paying bank cannot process a check image, the image can be printed, according to certain specifications, to create what is known as a substitute check, which is the legal equivalent of the original paper check. Without the requirement to preserve and use the original paper check, many of the traditional security features will no longer be effective. Thus, there is a need for a method or methods for detecting indicators of fraud in value documents such as a check using electronic images of the documents so that those documents can be identified for further investigation and scrutiny. Such methods would be particularly helpful at various stages of electronic check processing under Check 21.